Dug myself a huge dupe content hole, how much do I have to undo?

So it started out rather inocently for my transportation site. I created 4 boards in Pinterest about aspects of my business, local tourism, local tech business, competition from Uber, etc. I used the Pinterest toolbar button to pin daily news articles into each of the 4 boards. Within a few months i got 5000+ views, and re-pints, likes, followers etc.
Then the mistakes started. I put a Wordpress blog on my site and used IFTTT to post the pinned articles to 4 related Wordpress post categories. I also used IFTTT to post to a Tumblr blog, the company Facebook page, company Twitter account, LinkedIn,
Then it got worse. I stopped posting directly to everything other than Wordpress and got a Wordpress plug-in to post to the above sites and then signed up for a half dozen Facebook groups themed around the 4 Pinterest boards and then auto-posted from the Wordpress blog to all those sites. The new articles were good, and got lots of likes-re-tweets etc.
Then the ax fell over last weekend and the site went from #14 for the dominant key phrase to 24 on the third page. Never in our 15 year history have we would up on page three.
So here is the question: How deep do I have to go to undo all my mistakes. I am in the process of deleting the 2500 posts in Wordpress, do I have ot delete the tweets and Facebook posts etc.?

Would it be possible that you received some suspicious backlinks as a result of all this publicity? There may be other reasons I can't think of right now, but try to analyze all your automated social sharing and see if it wasn't the direct cause of the drop in search engine results but rather led to some other problem? If your content is of good quality, it would be a shame to delete it. There's also the chance some of your competitors outranked you....that can happen too.

Note that adblockers might block our captcha, and other functionality on BHW so if you don't see the captcha or see reduced functionality please disable adblockers to ensure full functionality, note we only allow relevant management verified ads on BHW.